Aluminum-zirconium antiperspirant salts with high peak 5 Al content

ABSTRACT

Disclosed are enhanced efficacy aluminum-zirconium antiperspirant salt compositions which exhibit an HPLC peak 5 area content of about 33% or more, preferably at least 45%, more preferably at least 50%, most preferably at least 55%. Especially preferred are aluminum-zirconium antiperspirant salt compositions which, in addition to the aforementioned high peak 5 content, also exhibit an HPLC peak 4 to peak 3 area ratio of at least 0.4, preferably at least 0.7. The aforementioned salt compositions will preferably have a metal (Al+Zr) to chloride (or anion) ratio of about 0.90 to about 1.00. Also disclosed are methods of making such antiperspirant salt compositions and aqueous solutions of such antiperspirant salt compositions. Further disclosed are topical compositions comprising a dermatologically acceptable carrier vehicle and a perspiration reducing effective amount of an aluminum-zirconium antiperspirant salt composition as described above.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation of application Ser. No.09/696,271 filed Oct. 25, 2000, now U.S. Pat. No.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to aluminum-zirconiumantiperspirant salts with high peak 5 aluminum content. The presentinvention also embraces methods of making these antiperspirant salts andcompositions containing these antiperspirant salts.

[0003] Aluminum-zirconium antiperspirant salts have been known forseveral decades. See, for example, U.S. Pat. No. 2,814,585 (Daley), U.S.Pat. No. 2,854,382 (Grad), GB 1,353,916 (Bolich), U.S. Pat. No.4,331,609 (Orr), U.S. Pat. No. 4,775,528 (Callaghan), U.S. Pat. No.4,871,525 (Giovanniello), U.S. Pat. No. 4,900,534 (Inward), U.S. Pat.No. 5,225,187 (Carmody), U.S. Pat. No. 5,296,623 (Katsoulis), U.S. Pat.No. 5,330,751 (Curtin), EP 653,203 (Rosenberg), U.S. Pat. No. 5,718,876(Parekh) and U.S. Pat. No. 5,955,064 (Giovanniello). Some of thesealuminum-zirconium antiperspirant salts are described as having enhancedefficacy, which means that they provide greater sweat reduction thanconventional antiperspirant salts.

[0004] The enhanced efficacy salts are typically differentiated fromconventional antiperspirant salts by reference to the various aluminumpeaks that can be identified when the salt is analyzed by size exclusionchromatography, typically HPLC (high pressure liquid chromatography). Asuitable chromatographic technique must be capable of resolving the Alinto at least four distinct peaks (labeled peaks 2 (or 1+2), 3, 4 and 5,), such as is shown in U.S. Pat. No. 5,330,751. Up to now, the enhancedefficacy salts have been described as having an increased peak 4 contentor an increased peak 4 to peak 3 ratio compared to conventional salts.(In some cases, enhanced salts have been described as having increased“band III” content by some authors, depending on the chromatographictechnique and nomenclature employed. Generally, bands I, II, III and IVof one system correspond to peaks 1+2 (band I), 3, 4 and 5 of the othersystem.) Typically, the known enhanced efficacy salts (measured as 10%solutions) have an HPLC peak 4 to peak 3 area ratio of 0.5 or higher,preferably at least 0.7, with at least 70%, preferably at least 80%, ofthe aluminum contained in peaks 3 and 4. Thus, the enhanced salts willtypically have a peak 4 content of at least 30% of the total aluminumcontained in all the peaks (measured by peak area). In contrast,conventional non-enhanced antiperspirant salts have a negligible peak 4content or a peak 4 to 3 area ratio less than 0.2, typically about 0.1.

[0005] Up to now, no one has suggested that peak 5 content plays anyrole in promoting the efficacy of antiperspirant salts. Aluminumantiperspirant salts are available as 2/3, 3/4, and 5/6 aluminumchlorohydrate (“ACH”) depending on the Al:Cl ratio (Al:Cl≅1, 1.7 and 2,respectively). While 2/3 ACH has a higher peak 5 content (typicallygreater than 50%) than 5/6 ACH (typically under 10%), it is not known tohave greater antiperspirant efficacy. (See, for example, Bretschneideret al, “Antiperspirant Efficacy”, in Proceedings of the 9th IFSCCCongress, Boston, Mass. 1976, pp. 263-75.) In fact, 5/6 ACH is the formused virtually exclusively in commercial antiperspirant products whichcontain ACH.

[0006] Of course, the most widely used antiperspirant products containaluminum-zirconium salts because they are more efficacious, especiallythe enhanced forms, as described above, with high peak 4 to peak 3ratio. Prior to the discovery of the enhanced Al−Zr salts, U.S. Pat. No.4,331,609 suggested that Al−Zr salts with a metal to chloride ratiobelow about 1.3 (e.g., 1.25) may be more efficacious than salts with ahigher metal to chloride ratio. However, this efficacy claim does notappear to have gained acceptance in the industry because salts with lowmetal to chloride ratios are not believed to have been produced incommercial quantities, at least not to any significant extent. Morerecently, U.S. Pat. No. 6,126,928 described certain polyhydric alcoholsolutions of the salts described in the aforementioned '609 patent.

[0007] Generally, all of the commercially used aluminum-zirconiumantiperspirant salts have a peak 5 content of less than 25%, moretypically less than 10%. Recently, Westwood Chemical has introduced anaqueous aluminum-zirconium chlorohydrate solution (sold under thetradename WZR 35BX3), which is said to have stable viscosity (i.e.viscosity does not increase significantly during normal storage) andappears to be made in accordance with U.S. Pat. No. 5,955,064. This salthas a somewhat elevated peak 5 content in the 20-25% range and arelatively low peak 4 content, typically less than 15%.

[0008] The enhanced efficacy aluminum-zirconium antiperspirant saltswhich are currently available commercially have one significantdrawback. They are unstable in aqueous solution, where they rapidlyrevert back to their non-enhanced state (for example, as evidenced by asignificant drop in the HPLC peak 4 to peak 3 area ratio). Consequently,these enhanced antiperspirant salts are generally only available inpowder form and must be formulated into finished formulations assuspended powders in order to retain their enhanced efficacy. Onesolution to this problem is disclosed in U.S. Pat. No. 6,042,816, wherestable aqueous solutions are prepared containing a calcium salt inaddition to the antiperspirant salt and an amino acid.

[0009] It would be highly desirable to provide enhanced efficacyaluminum-zirconium antiperspirant salts which are stable in aqueoussolution. This would make it possible to use the enhanced salts infinished formulations that require an aqueous salt form, such as thecurrently attractive clear gel compositions which have been successfullyintroduced in recent years. It would also be highly desirable to providean aluminum-zirconium antiperspirant salt which has even greaterantiperspirant efficacy than those currently available.

SUMMARY OF THE INVENTION

[0010] The present invention embraces enhanced efficacyaluminum-zirconium antiperspirant salt compositions which exhibit anHPLC peak 5 area content of about 33% or more, preferably at least 45%,more preferably at least 50%, most preferably at least 55%. Especiallypreferred are aluminum-zirconium antiperspirant salt compositions which,in addition to the aforementioned high peak 5 content, also exhibit anHPLC peak 4 to peak 3 area ratio of at least 0.4, preferably at least0.7, most preferably at least 0.9. The aforementioned salt compositionswill preferably have a metal (Al+Zr) to chloride (or anion) ratio ofabout 0.90 to about 1.00, more preferably about 0.90 to about 0.98, mostpreferably about 0.90 to about 0.96. The present invention also embracesmethods of making such antiperspirant salt compositions and aqueoussolutions of such antiperspirant salt compositions. The presentinvention further embraces topical compositions comprising adermatologically acceptable carrier and a perspiration reducingeffective amount of an aluminum-zirconium antiperspirant saltcomposition as described above.

[0011] It has been surprisingly found that aluminum-zirconiumantiperspirant salts with high peak 5 content (i.e.greater than 33%,preferably greater than 45%) are at least equivalent in antiperspirantefficacy to currently available enhanced efficacy salts (with high peak4 content) in powder form. However, unlike the currently availableenhanced salts which lose efficacy in aqueous solution, the high peak 5salts maintain their enhanced efficacy as aqueous solutions. Moreover,if the high peak 5 salts also have a peak 4 to 3 area ratio of at least0.4, they have even greater antiperspirant efficacy than currentlyavailable enhanced salts. This is very surprising because, although suchsalts have a high peak 4 to 3 ratio, they have a much lower total peak 4content than conventional enhanced salts because most of the aluminum ispresent in peak 5. Conventional enhanced Al−Zr salts typically have atleast 70%, more typically about 80% to 90%, of the aluminum in peaks 3and 4. The salts of the present invention, with high peak 5 content,have less than 67%, typically about 20% to about 50%, of the aluminum inpeaks 3 and 4.

DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is an HPLC chromatogram of a conventional enhanced efficacyaluminum-zirconium tetrachlorohydrate-gly antiperspirant salt(Al:Zr=3.6; M:Cl=1.4; peak 4:3=1.3; peak 5=17%).

[0013]FIG. 2 is an HPLC chromatogram of a high peak 5 enhanced efficacyaluminum-zirconium octachlorohydrate-gly antiperspirant salt of thepresent invention (Al:Zr=6.2; M:Cl=0.95; peak 4:3=1.1; peak 5=71.7%).

DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention embraces enhanced efficacyaluminum-zirconium antiperspirant salt compositions which, when analyzedby HPLC at about 10% (USP) concentration in water, exhibit an HPLC peak5 area content of at least 33% or more, preferably at least 45% or more,more preferably at least 50% or more, most preferably at least 55% ormore (up to about 80%, or even as high as 90%), based on the totalaluminum in the salt (as shown in HPLC peaks 2 to 5). The Al−Zr saltswill generally have the empirical formulaAl_(n)Zr(OH)_([3n+4−m(n+1)])(X)_([m(n+1)])−(AA)_(q) where X is Cl, Br, Ior NO₃, preferably Cl; n is 2.0 to 10.0, preferably 3.0 to 8.0; m is0.48 to 1.11 (which corresponds to a metal (Al+Zr) to anion (X) ratioM:X=2.1−0.9), preferably about 1.00 to about 1.11 (which corresponds toM:X=1.00−0.90), more preferably about 1.02 to about 1.11 (whichcorresponds to M:X=0.98−0.90), and most preferably about 1.04 to about1.11 (which corresponds to M:X=0.96−0.90); q is about 0.8 to about 4.0,preferably about 1.0 to 2.0; and AA is an amino acid such as glycine,alanine, valine, serine, leucine, or aminobutyric acid, preferablyglycine. These salts also generally have some water of hydrationassociated with them, typically on the order of 1 to 5 moles per mole ofsalt (typically, about 1% to about 16%, more typically about 4% to about13% by weight). A preferred antiperspirant salt is an aluminum-zirconiumchlorohydrate (i.e. X is Cl), more preferably an aluminum-zirconiumtetrachlorohydrate (Al:Zr=2−6; M:Cl=0.9−1.5) or aluminum-zirconiumoctachlorohydrate (Al:Zr=6−10; M:Cl=0.9−1.5), especially one with ametal to chloride ratio of about 0.90 to 1.00.

[0015] In addition to having a high peak 5 content, it is alsopreferred, for maximum efficacy, that the Al−Zr salt have an HPLC peak 4to peak 3 area ratio of at least 0.4, preferably at least 0.7, and mostpreferably at least 0.9. Generally, a substantial portion of the balanceof the aluminum not contained in peak 5 should be present in peaks 3 and4 (that is, substantially all of the aluminum is found in peaks 3, 4 and5). Thus, about 15% to about 67%, preferably about 20% to about 50%, ofthe aluminum will be present in peaks 3 and 4. In other words, the HPLCpeak 3 plus peak 4 areas will comprise about 15% to about 67%,preferably about 20% to about 55%, more preferably about 20% to about50%, of HPLC peaks 2 to 5.

[0016] The Al−Zr salt compositions of the present invention aremanufactured by mixing an aqueous solution of an aluminum antiperspirantsalt (preferably an enhanced aluminum antiperspirant salt as describedbelow) with an aqueous solution of a zirconium antiperspirant salt, eachsalt being present in an amount to provide the desired Al:Zr molarratio, then adjusting the metal:anion (M:X) ratio, if necessary, byaddition of an appropriate amount of HX. In order to drive theconversion of the aluminum polymer species toward the lowest molecularweight species which is found in peak 5, it is preferred to maintain alow metal (Al+Zr) to anion (X) ratio, typically M:X<1 (e.g. 0.90 to1.00, preferably 0.90 to 0.98), during the mixing of the aluminum andzirconium salt solutions. Typically the conversion will take about 0.5to 5 hours at room temperature (20-25° C.). The aqueous solution ofAl−Zr salt with high peak 5 content may be used or stored as an aqueoussolution, or it may be spray dried or vacuum dried to obtain the salt insolid powder form. Preferably, the salt will be dried to a solid whilethe peak 4:3 area ratio is above 0.4 to obtain a salt with maximumefficacy. Since the peak 4:3 ratio will decrease with time in solution,while the peak 5 content increases, it is a simple matter to monitor theAl peak content via HPLC over time and select a point to dry the saltwhere both the peak 5 content and the peak 4:3 ratio are at optimum highlevels.

[0017] Preferred aluminum salts for use as starting materials are thosehaving the general formula Al₂(OH)_(6-a)X_(a) wherein X is Cl, Br, I orNO₃, and a is about 0.3 to about 5, preferably about 0.8 to about 2.5,more preferably about 1 to about 2 (such that the Al to X mole ratio isabout 0.9:1 to about 2.1:1). These salts generally have some water ofhydration associated with them, typically on the order of 1 to 6 molesper mole of salt. Most preferably, the aluminum salt is aluminumchlorohydrate (i.e. X is Cl in the above formula), especially 5/6 basicaluminum chlorohydrate where a is about 1, such that the aluminum tochlorine mole ratio is about 1.9:1 to 2.1:1, typically about 1.95:1.Aluminum chlorohydrate is referred to as “ACH” herein.

[0018] Preferably, the ACH is an enhanced efficacy form, sometimeswritten as ACH′, which has an HPLC peak 4 to peak 3 area ratio of atleast 0.5, preferably at least 0.7, with at least 70%, preferably atleast 80%, of the aluminum contained in peaks 3 and 4. The enhancedefficacy aluminum chlorohydrates are readily made by heating a diluteACH solution (e.g. about 10% salt concentration by weight) at about80-100° C. for about 4 to 20 hours. It has been found that the greatestantiperspirant efficacy in the final Al−Zr antiperspirant salt with highpeak 5 can be obtained when an enhanced efficacy aluminum antiperspirantsalt is used as one of the starting materials.

[0019] Preferred zirconium salts for use as starting materials are thosehaving the general formula Zr(OH)_(4-b)X_(b) wherein X is Cl, Br, I, orNO₃, preferably Cl; and b is about 0.7 to about 4.0, preferably about2.2 to about 4.0 (i.e., Zr:X≅0.45−0.25), more preferably about 3.4 toabout 3.8 (Zr:X≅0.29−0.26). Although written for convenience asZr(OH)_(4-b)X_(b), this salt is intended to include the well-knownzirconyl oxychloride and zirconyl hydroxychloride, which is also oftenwritten as ZrO(OH)_(2-b)Cl_(b) (where b, in this instance, is about 1 to2). The zirconium salts also generally have some water of hydrationassociated with them, typically on the order of 1 to 7 moles per mole ofsalt. In addition, the zirconium salt will contain an amino acid, asdescribed above, to prevent gellation. Preferably the zirconium salt iszirconyl hydroxychloride of the formula Zr(OH)_(2-b)Cl_(b) wherein b isabout 0.7 to about 4.0, preferably about 2.2 to about 4.0 (i.e.,Zr:Cl≅0.45−0.25), more preferably about 3.4 to about 4.0(Zr:Cl≅0.29−0.25), most preferably about 3.4 to about 3.8(Zr:Cl≅0.29−0.26). Zirconium salts with a low Zr:X ratio are preferredbecause such salts tend to have a lower molecular weight than otherzirconium salts. It is theorized that the use of low molecular weightzirconium salts results in higher antiperspirant efficacy in the finalAl−Zr salt. In addition, the use of zirconium salts with a low Zr:Xratio also facilitates the manufacture of the preferred Al−Zr salt witha low metal:X ratio.

[0020] As an alternative to or in conjunction with the above-describedaluminum and zirconium salts, it is also possible to employ aluminumchloride (AlC₃) and/or zirconium basic carbonate (Zr₂(OH)₄(CO₃)₂.nH₂O)as starting materials, provided that the molar ratio of the variousreactants is adjusted to arrive at the desired molar ratio of thealuminum, zirconium, hydroxyl and chloride moieties in the final Al−Zrsalt prepared.

[0021] A preferred high peak 5 enhanced salt is aluminum-zirconiumchlorohydrate (i.e. X is Cl), referred to herein as “E⁵AZCH”, which hasan Al:Zr ratio of about 2 to about 10 and a metal:Cl ratio of 0.90 to1.00, preferably 0.90 to 0.98. This salt will exhibit an HPLC peak 5area content of about 45% or more, preferably at least 50% or more, morepreferably at least 55% or more, up to about 90%, based on the totalaluminum in the salt. To achieve maximum efficacy, this salt will alsopreferably have an HPLC peak 4 to peak 3 area ratio of at least 0.4,more preferably at least 0.7, and most preferably at least 0.9. It hasbeen surprisingly found that such a salt has superior antiperspirantefficacy, and more surprisingly will maintain its superiorantiperspirant efficacy, even when stored as an aqueous solution. Thisis a distinct advantage over previously known enhanced antiperspirantsalts, whose efficacy deteriorates in aqueous solution.

[0022] The antiperspirant salts of the present invention may beformulated into topical compositions such as liquids (e.g., for roll-onor porous applicators), lotions, creams, gels, soft-solids, solidsticks, etc. Such compositions will comprise the antiperspirant salt ina perspiration reducing effective amount and a dermatologicallyacceptable carrier.

[0023] In particular, aqueous solutions of these antiperspirant saltsmay be directly utilized in oil-in-water and water-in-oil emulsions,such as the currently popular clear gel formulations, or in otheraqueous based compositions such as aqueous based roll-ons. Preferredaqueous liquid compositions will comprise about 8% to about 45% (USP) byweight, preferably about 18% to about 38% (USP) by weight,antiperspirant salt and about 20% to about 90%, preferably about 45% toabout 80%, water, such aqueous compositions optionally including otherwater soluble cosmetic ingredients (e.g. ethanol or polyhydric alcohol).These aqueous solutions may be stored indefinitely without significantloss of efficacy, unlike solutions of conventional enhanced efficacysalts, and may be diluted to an appropriate concentration (e.g. 6%-22%USP) for topical application when formulated into a commercial product.

[0024] It is also possible to make a solution of E⁵AZCH in a liquidpolyhydric alcohol such as propylene glycol. The liquid polyhydricalcohol will typically have from three to six carbon atoms and from twoto six hydroxyl groups. Such a solution may be readily obtained byadding the polyhydric alcohol to an aqueous solution of E⁵AZCH asdescribed above, then evaporating off the water under vacuum (see, forexample, U.S. Pat. No. 5,643,558). Such a polyhydric alcohol compositionmay advantageously comprise about 8% to about 45% (USP) of saidantiperspirant salt. This product can then be readily formulated intotopical antiperspirant compositions which use a polyhydric alcoholvehicle, such as clear sticks gelled with dibenzylidene sorbitol orother gellants (see, for example, U.S. Pat. No. 5,705,171).

[0025] It is especially preferred to produce the E⁵AZCH salts of thepresent invention in solid powder form, for example by spray drying orvacuum drying the aqueous solution in which these salts are produced.The powdered antiperspirant salts may then be formulated into any knowntype of topical composition which utilizes powdered salts, including, inparticular, liquid roll-on, cream, soft solid and solid stickformulations in which the powdered salt is suspended in an anhydrous,dermatologically acceptable carrier, particularly a carrier comprising asilicone (e.g. cyclomethicone, dimethicone, etc.), typically at aconcentration of about 6% to about 22% (USP) active by weight.

[0026] The present invention also embraces a method of inhibiting orreducing perspiration by topically applying an effective amount of anantiperspirant composition as described herein to the skin of a human,preferably to the axilla, where such reduction in perspiration isdesired by the user. An effective amount is that amount which providesat least a 20% sweat reduction, preferably at least a 40% sweatreduction, when tested in accordance with a standard hot room thermalefficacy protocol, and most preferably that amount which reducesperspiration to a degree that is noticeable by the user. Typically, theamount of antiperspirant composition applied will range from about 0.1gram to about 1.0 gram per axilla depending on the formulation or suchamount as will deliver about 0.01 to about 0.25 gram of antiperspirantactive per axilla.

[0027] The present invention may be further illustrated by the followingexamples in which the parts and percentages are by weight. In theseexamples, the abbreviation ACH means standard efficacy (i.e.non-enhanced) 5/6 basic aluminum chlorohydrate with an Al:Cl ratio ofabout 1.95. Unless otherwise stated, the ACH used in the examples has aconcentration of about 42% USP active (nominally 50% by weight). Theabbreviation ACH′ means an enhanced efficacy form of this salt, that isone having an HPLC peak 4 to peak 3 area ratio of at least 0.7 with atleast 80% of the aluminum contained in peaks 3 and 4. The ACH′ is madeby diluting ACH with water to form a solution of about 10%concentration, heating the dilute ACH solution at about 85° C. for about16 hours, then rapidly concentrating the ACH′ by vacuum evaporation (forexample, using a falling film evaporator) to a concentration of about42% USP active and cooling to room temperature. The ACH′ must be usedwithin several hours of preparation, preferably as soon as possibleafter preparation, in order to insure that it has the desired high peak4 to peak 3 ratio.

[0028] The abbreviation ZHCG means zirconyl hydroxy chloride-glycine(Zr:Gly≅1). When referring to this material, the Zr:Cl ratio (e.g.Zr:Cl=0.28) will be indicated in parentheses following the abbreviation.The ZHCG may be prepared by reacting zirconium basic carbonate with anappropriate amount of HCl to achieve the desired Zr:Cl ratio, thenadding the appropriate amount of glycine. The aqueous ZHCG used in theexamples has a Zr content of about 8% (Zr:Cl 0.26) to about 19% (Zr:Cl1.1) by weight Zr.

[0029] The abbreviation AZCH means aluminum-zirconium chlorohydrate-gly(standard efficacy), EAZCH means a conventional enhanced efficacy AZCHwith high peak 4:3 ratio, and E⁵AZCH means an enhanced efficacy AZCH ofthe present invention with high peak 5.

COMPARATIVE EXAMPLE

[0030] In accordance with the technique described in U.S. Pat. No.4,775,528, freshly prepared aqueous ACH′ solution is mixed with aqueousZHCG^(a) (Zr:Cl=0.67) in the appropriate molar ratio to provide anaqueous solution of enhanced efficacy aluminum-zirconiumtetrachlorohydrate (˜33% USP) with an Al:Zr mole ratio of about 3.6 anda M:Cl mole ratio of about 1.4. This solution is spray dried to obtainthe EAZCH salt in solid powder form. A sample of this antiperspirantsalt, when dissolved in water at about 10% concentration and analyzed byHPLC within a few minutes of preparation, produces a chromatogram asshown in FIG. 1. From this chromatogram, it can be seen that more than80% of the aluminum is contained in peaks 3 and 4, with the peak 4:3area ratio being about 1.3, while the amount of peak 5 aluminum is about17% of the total aluminum. As is well-known, this salt cannot beusefully employed in aqueous form because the peak 4:3 ratiodeteriorates very quickly, thus reverting to a standard efficacy salt.

[0031] The above-described enhanced efficacy salt may be tested forthermal efficacy (i.e. hot room sweat reduction) using volunteerpanelists in a standard hot room protocol. The test product (vehicleplus enhanced efficacy salt) is applied to one axilla and controlproduct (vehicle only or vehicle plus standard efficacy antiperspirantsalt) is applied to the other axilla. The above-described enhancedefficacy salt typically provides a sweat reduction of about 57-62%versus about 47-52% obtained with standard efficacy salt, when suspendedas an 18-19% USP active in a liquid volatile silicone carrier vehicle.Also, a freshly prepared aqueous solution of the above-describedenhanced efficacy salt (20% USP active) typically provides a sweatreduction of about 63-69% versus about 48-54% obtained with standardefficacy salt in aqueous solution at the same concentration.

EXAMPLE 1

[0032] Freshly prepared aqueous ACH′ solution (or in one case, sample H,standard ACH solution) is mixed with aqueous ZHCG solution (as definedbelow) in the appropriate molar ratio to provide the desired Al:Zr ratioalong with sufficient HCl, as needed, to provide the desired M:Cl ratio,thus forming aqueous solutions of enhanced efficacy aluminum-zirconiumchlorohydrates (about 30-35% USP active) with Al:Zr mole ratios, M:Clmole ratios, and HPLC peaks as shown in Table 1 below. The various ZHCGsolutions used are as follows: ZHCG^(b) (Zr:Cl=0.26-0.28), ZHCG^(c)(Zr:Cl=0.44−0.45), and ZHCG^(d) (Zr:Cl=0.44−0.45), the ZHCG^(d) being ablend of about 60 parts ZHCG^(b) and about 40 parts ZHCG^(f)(Zr:Cl=1.05−1.10). A portion of each antiperspirant salt solution isretained for further testing, and the remainder is spray dried torecover the antiperspirant salt as a powder. Antiperspirant salt B, whendiluted to about 10% concentration, produces an HPLC chromatogram asshown in FIG. 2. TABLE 1 Enhanced Al—Zr Salts With High Peak 5 E⁵AZCHZHCG Al:Zr M:Cl Peak 5 Peak 4:3 A b 10 0.94 53.9 0.41 B¹ b 6.2 0.95 71.71.1 C b 10 0.94 53.7 0.46 D d 2 0.92 51.8 1.9 E c 2.1 0.95 48.5 2.4 F d2 0.92 57.7 1.72 G² d 2 0.9 74.7 0.17 H³ d⁴ 2 0.94 57.2 0.2 J b 4.6 0.9650.0 1.7 K b 7.8 1.15 33.7 2.0

EXAMPLE 2

[0033] The above-described high peak 5 enhanced efficacy salts ofExample 1 are tested for thermal efficacy (i.e. hot room sweatreduction) using volunteer panelists in a standard hot room protocol.The test product is applied to one axilla and control product is appliedto the other axilla in an AvB comparison. In all cases, the test productcomprises vehicle (as described below) plus high peak 5 enhancedefficacy salt (E⁵AZCH). The control product comprises vehicle plusconventional enhanced efficacy (high peak 4:3) antiperspirant salt(EAZCH), except where the vehicle is a clear gel formulation, in whichcase a standard efficacy salt (AZCH) is used because of the instabilityof the conventional enhanced salt in aqueous formulations. To counteractthis instability, the formulation identified as “Aqueous” below, isfreshly prepared with powdered EAZCH just prior to being tested. Theformulations tested are set out below and the results are shown in Table2. The results are reported as the average sweat reduction (“S.R.”) gainover the control (i.e. the absolute percentage point increase in sweatreduction over the control). Aaueous Roll-On 20% USP AP active 20.0% APactive q.s. water 75.1% Cyclomethicone  3.5% Quaternium-18 hectorite 1.0% Propylene carbonate  .4% Fragrance Clear Gel Solid 23.5% AP active23.5% AP active 39.8% Water 51.9% Cyclomethicone  8.7% Propylene Glycol13.5% Stearyl alcohol 10.0% Ethanol  3.0% Hydrogenated castor oil  9.7%Dimethicone  4.0% Myristyl myristate  8.1% Cyclomethicone (and)  1.8%Silica    Dimethicone copolyol  2.3% Fragrance/Silk Powder  0.2%Fragrance

[0034] TABLE 2 Thermal Efficacy of Al—Zr Salts With High Peak 5 E⁵AZCHVehicle Control Avg. S.R. Gain Over Control A Roll-On EAZCH  5.8 (p =0.0001) B Aqueous¹ EAZCH  7.0 (p = 0.004) C Aqueous EAZCH  4.2 (p =0.025) C Clear Gel AZCH 15.9 (p = 0.0001) C Clear Gel² AZCH 13.3 (p =0.0001) D Aqueous EAZCH  5.9 (p = 0.0001) D Aqueous EAZCH  4.6 (p =0.002) D Roll-On EAZCH  8.7 (p = 0.0001) E Aqueous EAZCH  1.3 (N.S.)⁴ FAqueous EAZCH  4.5 (p = 0.059) F Solid EAZCH  4.0 (p = 0.012) G³ SolidEAZCH  2.1 (N.S.) H³ Aqueous EAZCH  0.3 (N.S.) J Aqueous EAZCH  4.3 (p =0.001) K Aqueous EAZCH  1.7 (N.S.)

[0035] From the above data, it can be seen that the preferred enhancedantiperspirant salts of the present invention (high peak 5 and peak4:3>0.4; e.g. salts A, B, C, D, F and J) are more efficacious thanconventional enhanced antiperspirant salts (high peak 4:3 ratio, but lowpeak 5). This result is surprising because the amount of aluminumcontained in peaks 3 and 4 of the E⁵AZCH salt is considerably reducedversus the EAZCH (<50% vs. >80%). Even more surprising is the fact thatthe E⁵AZCH salt (salt B) retains its superior efficacy when stored as aconcentrated aqueous solution (in this case, for 1.5 years).Conventional enhanced salts lose their enhanced state in aqueoussolution.

[0036] When formulated as a clear gel, the high peak 5 salt (salt C) issubstantially more efficacious than the current commercial clear gelproduct, which must use a standard efficacy salt, and this high peak 5salt maintains its high efficacy even after storage of the clear gel athigh temperature. In addition, the high peak 5 salts with low peak 4:3ratio (salts G and H) are surprisingly just as efficacious as theconventional enhanced salt with high peak 4:3 ratio. Such salts, whilenot quite as efficacious as the preferred salts, can provide a usefulalternative to the currently available enhanced salts, particularlywhere improved efficacy is desired in aqueous based formulations wherecurrent enhanced salts cannot be used. Similarly, salt K, with only amodest peak 5 content (peak 5=33.7%) is just as efficacious as aconventional enhanced salt and could be an advantageous alternative,particularly in aqueous based formulations. Although salt E proved to bejust as efficacious as the conventional enhanced salt and would thusoffer the same advantage as salts G and H, it is believed that furthertesting would reveal that an E⁵AZCH with a peak 5 content of 48% wouldbe somewhat more efficacious than a conventional enhanced salt.

[0037] Throughout the specification reference to HPLC analysis meansthat chromatograms are obtained as follows: Salt solutions are evaluatedfor aluminum polymer distribution by HPLC at a concentration of about10% (USP) Al−Zr salt. If the solution to be analyzed is at a higher saltconcentration, it is diluted with sufficient water to bring the saltconcentration to about 10%. A 1.0 μL sample is injected into a WatersU6K injector, then pumped through a 4.6 mm×500 mm column packed withNucleosil 100-5 silica with pore size of 100 angstroms and particle sizeof 5 μm (Keystone Scientific Inc.) using a 0.01M aqueous nitric acidsolution as the eluant. The flow rate of the mobile phase is controlledat 0.5 mL/min with an LDC/Milton Roy Constametric-II metering pump(ThermoQuest Inc.). HPLC profiles are recorded and processed with acomputerized system that includes the Millennium 32 ChromatographyManager software from Waters Corp. A Waters 2410 differentialrefractometer is used as the refractive index detector. The HPLCprofiles are read from left to right (higher to lower molecular weight).Following this technique, peak 3 typically appears at a retention timeof about 11.0-12.0 minutes (Kd≅0.58-0.61), peak 4 typically appears at aretention time of about 11.9-12.9 minutes (Kd≅0.62-0.72), and peak 5typically appears at a retention time of about 13.3-14.0 minutes(Kd≅0.83-0.91). Naturally, of course, other HPLC techniques which usedifferent column materials, eluants and flow rates can be used providedthat they sufficiently resolve peaks 3, 4 and 5 with an acceptabledegree of precision (i.e. the technique must be capable of resolving theAl into at least four distinct peaks, with the first Al peak beinglabeled peak 2 or peak 1+2). Obviously, such other techniques may placepeaks 3, 4 and 5 at different retention times from those given above.

[0038] It should be noted that reference throughout this application toweight percent of antiperspirant salt is intended to be calculated asanhydrous weight percent in accordance with the new U.S.P. method. Thiscalculation excludes any bound water and glycine. For aluminum-zirconiumchlorohydrate, the calculation is as follows:

%AZCH=%Al{26.98y+92.97+17.01[3y+4−(y+1)/z]+35.45(y+1)/z}126.98y

[0039] where y=Al/Zr ratio and z=metal/Cl ratio.

[0040] For reference purposes, calculation of antiperspirant salt weightpercent in accordance with the U.S.P. method compares to the previouslyused standard industry method as follows: 50% AZCH (std)≅38.5% USP.

What is claimed is:
 1. An aluminum-zirconium chlorohydrate having ametal (Al+Zr) to chloride ratio of 0.90 to 1.00.
 2. Thealuminum-zirconium chlorohydrate of claim 1 which is analuminum-zirconium tetrachlorohydrate.
 3. The aluminum-zirconiumchlorohydrate of claim 1 which is an aluminum-zirconiumoctachlorohydrate.
 4. The aluminum-zirconium chlorohydrate of claim 1having the formula Al_(n)Zr(OH)_([3n+4−m(n+1)])(Cl)_([m(n+1)])−(Gly)_(q)wherein n is 2.0 to 10.0, m is 1.00 to 1.11, and q is about 0.8 to about4.0.
 5. The aluminum-zirconium chlorohydrate of claim 4 wherein q isabout 1.0 to 2.0.
 6. The aluminum-zirconium chlorohydrate of claim 5wherein m is about 1.02 to about 1.11.
 7. The aluminum-zirconiumchlorohydrate of claim 5 wherein m is about 1.04 to about 1.11.
 8. Thealuminum-zirconium chlorohydrate of claim 5 which, when analyzed by HPLCas a 10% aqueous solution using conditions capable of resolving thealuminum into at least four successive peaks (labeled peaks 2 to 5),exhibits an HPLC peak 5 area of at least 45% and an HPLC peak 4 to peak3 area ratio of at least 0.4, wherein substantially all of the aluminumis found in peaks 3, 4 and
 5. 9. The aluminum-zirconium chlorohydrate ofclaim 5 wherein n is 2 to
 6. 10. The aluminum-zirconium chlorohydrate ofclaim 5 wherein n is 6 to
 10. 11. The aluminum-zirconium chlorohydrateof claim 1 made with a zirconyl hydroxychloride of the formulaZr(OH)_(4-b)Cl_(b) wherein b is about 2.2 to about 4.0 so that the Zr:Clratio in said zirconyl hydroxychloride is between 0.45 and 0.25.
 12. Thealuminum-zirconium chlorohydrate of claim 1 made with a zirconylhydroxychloride of the formula Zr(OH)_(4-b)Cl_(b) wherein b is about 3.4to about 4.0 so that the Zr:Cl ratio in said zirconyl hydroxychloride isbetween 0.29 and 0.25.
 13. The aluminum-zirconium chlorohydrate of claim2, 3, 5, 9, or 10 made with a zirconyl hydroxychloride of the formulaZr(OH)_(4-b)Cl_(b) wherein b is about 3.4 to about 4.0 so that the Zr:Clratio in said zirconyl hydroxychloride is between 0.29 and 0.25.
 14. Thealuminum-zirconium chlorohydrate of claim 1, 2, 3, 5, 9, 10 or 12 insolid powder form.
 15. An aqueous composition comprising water and,dissolved therein, an aluminum-zirconium chlorohydrate according toclaim 1, 5, 9, 10 or
 12. 16. The aqueous composition of claim 15comprising about 8% to about 45% (USP) of said aluminum-zirconiumchlorohydrate.
 17. A composition comprising a liquid polyhydric alcoholand, dissolved therein, an aluminum-zirconium chlorohydrate according toclaim 1, 5, 9, 10 or
 12. 18. The composition of claim 17 comprisingabout 8% to about 45% (USP) of said aluminum-zirconium chlorohydrate.19. A clear antiperspirant gel composition comprising a water-in-oilemulsion having a water phase and an oil phase, wherein the water phasecomprises an aqueous composition according to claim
 15. 20. A topicalantiperspirant composition comprising a dermatologically acceptablecarrier and a perspiration reducing effective amount of analuminum-zirconium chlorohydrate according to claims 1, 5, 9, 10 or 12.21. The topical antiperspirant composition of claim 20 wherein saidcarrier is an anhydrous carrier and said antiperspirant salt is in solidpowder form suspended in said anhydrous carrier.
 22. The topicalantiperspirant composition of claim 21 wherein said anhydrous carriercomprises a silicone.
 23. The topical antiperspirant composition ofclaim 20 in the form of a liquid, lotion, cream, gel, soft-solid, orsolid stick.
 24. A method of reducing perspiration from human skincomprising applying to human skin a topical antiperspirant compositionaccording to claim
 20. 25. A method of reducing perspiration from humanskin comprising applying to human skin an aluminum-zirconiumchlorohydrate according to claim 1, 5, 9, 10 or
 12. 26. A method ofpreparing an aluminum-zirconium chlorohydrate of the formulaAl_(n)Zr(OH)_([3n+4−m(n+1)])(Cl)_([m(n+1)])−(Gly)_(q) wherein n is 2.0to 10.0, m is 1.00 to 1.11, and q is about 0.8 to about 4.0, whichmethod comprises mixing an aqueous solution of an aluminum chlorohydrateof the formula Al₂(OH)_(6-a)Cl_(a) wherein a is about 1 to about 2, witha zirconyl hydroxychloride of the formula Zr(OH)_(4-b)Cl_(b) wherein bis about 2.2 to about 4.0, each salt being present in an amount toprovide an Al:Zr molar ratio of 2.0 to 10.0, and, if necessary,adjusting the metal (Al+Zr) to chloride ratio (M:Cl) to 0.90 to 1.00 byaddition of an appropriate amount of aqueous HCl.
 27. The method ofclaim 26 wherein b is about 3.4 to about 4.0 in said zirconylhydroxychloride.
 28. The method of claim 26 wherein said aluminumantiperspirant salt has an HPLC peak 4 to peak 3 area ratio of at least0.5 with at least 70% of the aluminum contained in peaks 3 and
 4. 29.The method of claim 26, 27 or 28 which additionally comprises dryingsaid solution to obtain said aluminum-zirconium chlorohydrate in solidform.